Meeting Abstract

P3.181  Tuesday, Jan. 6  Investigating the evolutionary mechanisms in the adaptive radiation of cichlid fishes of Lake Victoria basin BEZAULT, E.**; MWAIKO, S.; SEEHAUSEN, O.; EAWAG and University of Bern, Switzerland; Tanzania Fisheries Research Institute and EAWAG, Kastanienbaum, Switzerland; EAWAG and University of Bern, Switzerland etienne.bezault@eawag.ch

The Lake Victoria cichlid superflock, comprising the related radiations of lakes Victoria, Edward, Albert and Kivu, is an example of the most explosive adaptive radiation, with more than 500 species evolved within the last 15-100,000 years, and the most recent in the East African Great Lakes. The repetitive occurrence of the same adaptively important traits in unrelated taxa within and between lakes makes the superflock, and especially the Lake Victoria flock, an ideal model for studying adaptive radiation in shape, ecology and behaviour. However its very recent origin is a challenge for phylogenetic reconstruction because of incomplete lineage sorting and potential for hybridization. In contrast with the well supported monophyly of the mtDNA lineage (d-loop & ND2), the nuclear data (AFLP) suggest that the nuclear genomic diversity of Lake Victoria superflock received contributions from several unrelated lineages that hybridized when seeding the radiations. This could explain the segregation of numerous polymorphisms within and between radiations of the superflock. Furthermore, the shallow levels of species structure at neutral loci within Lake Victoria cichlids contrasts with strong differences based on adaptive genetic and phenotypic diversity. These data raise the possibility that functional traits can be transferred between species by the interaction of hybridization and selection. This is investigated by studying a large number of genomic markers (AFLP) to i) reconstruct a species level majority-genome phylogeny for the superflock and ii) to detect loci under selection associated with adaptively important phenotypic traits.